...phrases like "drive carefully!" and "I can't wait for Spring!" and "Dude!" outnumber "meaningful" exchanges. These supposedly meaningless phrases in everyday talk are the equivalent of literary style in writing. Just as you don't read Ulysses as a guide to Dublin or Lady Chatterley's Lover as a gardening manual, so you don't talk to your friends and acquaintances to exchange information or commands. You talk for the pleasure of knowing another person, and being known in turn. Pragmatic language is what marks you as you. Therefore it's important in all exchanges in which your identity—the fact that it's you talking—matters more than the formal information you're communicating. For your sake, I hope that's most exchanges. Then too, if you want to explain how language evolved (a subject shunned by many students of idealized language), you have to consider what this complex and expensive cognitive system could do for creatures that didn't, at first, exchange formally defined information.